This invention relates to tire building machines and especially to turrets having two drums for the assembly of tire components with the drums in more than one position. It is especially relevant to tire building machines for building relatively heavy tires, such as truck tires for highway use where precision building is important for safety and performance.
Heretofore, as shown in U.S. Pat. No. 5,730,829, a two drum turret for tire assembly has been provided with a pair of drums mounted on a turret which is rotatable on a turret drive shaft. The turret is rotated on the turret drive shaft 180 degrees for interchanging the positions of the drums and adding different tire components. This arrangement has been satisfactory for building passenger tires, however, with larger truck tires, there may be problems building a tire with precision because the increased weight of the larger size drums and the weight of the truck tires make it difficult to maintain alignment of the drum spindles. Also, the twisting of the turret drive shaft due to driving the shaft at a distance from the turret makes it difficult to move the heavier drums and tire assemblies into predetermined positions for application of the tire components. Provision of an outboard support for the turret drive shaft has been proposed for a turret in Russian patent SU682-389, however, no provision for controlling the rotation of the turret with precision is provided.
In accordance with the present invention, a tire building turret and turret rotating apparatus is provided which not only has an outboard support but is provided with a direct drive to eliminate twisting of the drive shaft rotating the turret so that precise positioning of the drum is obtained. Also, the drum shafts are mounted in the rotatable turret frame to permit elongation of the drum shafts with a minimum of axial movement of the drums relative to the frame. Adjustable drum shaft bearings are provided to position the axles in the rotatable turret frame to further insure the building of tires with precision on the drum.
In accordance with one aspect of the invention, there is provided a tire building apparatus comprising a turret support housing, a turret frame rotatably mounted on the housing, a first drum rotatably mounted on the turret frame at one side of the frame, a second drum rotatably mounted on the turret at an opposite side of the frame, characterized by power means mounted on the housing and in direct driving engagement with the turret frame for rotating the turret frame directly from the turret support housing to position the first drum and the second drum in predetermined positions for application of tire components.
In accordance with another aspect of the invention, there is provided a tire building apparatus comprising a turret frame mounted for rotation on a turret support shaft and having a first drum rotatably mounted on a first shaft supported in spaced apart first and second bearings and a second drum rotatably mounted on the second shaft supported in the housing for rotation on third and fourth bearings characterized by the spaced apart first bearing being a fixed bearing adjacent the first drum and the second bearing being spaced from the first bearing and being movable to maintain a substantially fixed axial position of the first drum while permitting elongation of the first shaft and the third bearing being a fixed bearing adjacent the second drum and the fourth bearing being spaced from the third bearing and being movable axially to maintain a substantially fixed axial position of the second drum while permitting elongation of the second shaft.